Could be tires - could be input shaft - could be warped/bent rim - could be could be could be.
First thing to look for when you think a halfshaft might be a problem - grease. Check inside the wheel wells for any grease on the control arm - and on the sway bar - it tends to accumulate on the outermost sway bar bushing. Half shafts tend to "let you know" when they are going out - you will either have a noticeable noise when turning corners, or even when just cruising down the highway. In corners, you'll hear a sort of "wharble" - sounds like something is out of round, and is often accompanied by tire squealing - on the highway it will sound like a growling noise - almost like excessive road noise. You may want to check the tie rods as well - jack the car up, grab the tire and 3 and 9 o'clock and try to move it left to right, do the same at 12 and 6 o'clock. If it moves much at all - that could be your culprit- and yes it can/will cause vibrations.
If you check those and all is well - or don't have any of those other symptoms...get the tires/wheels balanced - make sure to have them tell you what corrections they made and where. If that still doesn't fix it - I would recommend pulling the driver's side halfshaft and checking the input shaft on the transmission - if it starts puking fluid as soon as you pull the halfshaft off - and the input shaft is loose - there is your problem...and I'm sorry. At that point - call Trannyman.
-Swash